The present invention relates to a pressing device for extracting liquid from an aqueous pulp web, said pressing device having two press rolls that form between them a nip, a first press roll having its two ends supported in first bearing blocks and being stationarily fixed at least on one end, and the second press roll being supported by its two ends in second bearing blocks that can be braced against the first bearing blocks by means of tension members, which tension members allow the press rolls to perform a relative movement in the axial direction under load.
A pressing device of this kind is known from U.S. Pat. No. 5,291,826.
In the case of the known pressing device, two press rolls are arranged in parallel one to the other, forming between them a press nip. Given the fact that the first bearing blocks and the second bearing blocks are braced by means of tension elements, a short flux of force is obtained for the transmission of the pressing force in the press nip, which avoids stresses on the elements of the supporting structure. Thus, the supporting structure only has to transmit the weight of the press proper, not the high pressing forces. This results in a simpler, less heavy and space-saving structure. In the known pressing device, the tension elements consist of a central portion resembling a leaf spring, and hammer hands on their ends that are held in grooves provided in the bearing blocks. Thus, the bearing blocks are rigidly connected with the hammer heads of the tension elements. At the same time, the tension elements, being flexible in the axial direction of the press rolls, allow the press rolls to bend relative one to the other, and to be axially displaced a certain amount relative one to the other during operation, as a consequence of high pressing forces or due to variations in length that may be caused, for example, by thermal conditions. In the unloaded condition of the pressing device, the tension elements are biased either not at all, or only very slightly.
Further, both press rolls have one of their ends fixed stationarily on the frame, via their bearing blocks. While this is achieved for the first roll by rigidly connecting a bearing block with the frame, the second press roll is provided for this purpose, on its opposite end, with a sliding guide by means of which the bearing block of the second press roll is fixed on the machine frame in the axial direction, but is capable of being displaced in the vertical direction.
It has been found in the case of the known pressing device that the tension elements, by means of which the pressing forces are transmitted during operation between the two press rolls, may be subjected to considerable bending stresses, which has a detrimental effect on the load capacity of the tension elements.